It is known per se, for operating lamps, in particular discharge lamps, or other light-producing apparatuses such as LEDs, to use electronic ballasts. This term in this case means a wide variety of electronic operating devices, and in particular those which use, for example, an inverter to produce a supply voltage, which is matched in terms of voltage, frequency and/or other relevant parameters, from a supply voltage of the ballast for the light-producing apparatus. One important application is electronic ballasts having inverters which operate discharge lamps primarily, but not exclusively, low-pressure discharge lamps. Such electronic ballasts are in many cases equipped with controllers which require an internal timing unit in the ballast. In particular, the operating frequency of a discharge lamp can be derived from the signal from the internal timing unit.